Modern commercial bakeries of the type utilized in the manufacture of bread, rolls, and similar bakery products employ a large oven enclosure and a conveyor system extending therethrough. Uncooked dough is deposited into bakery pans which are transported by the conveyor through the oven. The speed of operation of the conveyor is coordinated with the length of the conveyor such that the dough is fully baked when a single pass through the oven has been completed.
Heretofore it has not been practical to position conveyor drive assemblies inside the oven because the elevated temperature within the oven would cause the component parts of the conveyor drive assembly to fail. Prior to the present invention oven conveyor chains have been driven by a single conveyor drive assembly located outside of the oven which overcomes the problem of excessive heat but is unsatisfactory because the entire length of the conveyor is pulled through the oven from a single location. This causes excessive load and chain pull on the conveyor chain as well as more stress on the chain bearings. Also, if the single conveyor drive assembly goes down the entire system is down.
The present invention comprises an oven drive system which overcomes the foregoing difficulties which have long since characterized the prior art. In accordance with the broader aspects of the invention oven drive assemblies for a bakery oven comprise a drive motor and a speed reducer located outside of the bakery oven, a drive shaft extending into the oven, and a conveyor chain drive caterpillar located inside the oven. The drive shaft preferably configured for minimal heat transfer through the drive shaft to the components of the oven drive assembly located external to the oven.
All of the components of the conveyor chain drive caterpillar and the drive shaft comprise materials having similar coefficients of thermal expansion such that the components can withstand high temperatures within the oven while minimizing induced thermal stress caused by fluctuation in oven temperature. This facilitates the positioning of oven drive assemblies comprising the invention at substantially equally spaced intervals along the conveyor chain thereby reducing stress on the conveyor chain and maximizing conveyor chain life. Also, failure of one of the oven drive assemblies does not result in the entire system going down as has been the case previously. Rather, the remaining oven drive assemblies compensate for the increased load by operating at elevated stress levels until the failed oven drive assembly can be repaired.